It is known in the art of rail-supported vehicles or rolling stock to connect multiple units into a single train to enable transportation of increased amounts of materials or passengers. This connection is achieved by means of a coupling mechanism between cars, and numerous coupling mechanisms have been developed and standardized over the years. One example of such a coupling mechanism is the Janney coupler or knuckle coupler, which was subject of U.S. Pat. No. 138,405 and is in wide usage under specifications overseen by the Association of American Railroads, or AAR. An example of a prior art coupler is shown in FIG. 1a, the coupler 1 comprising a head 2 and pivot end 4 connected by a shank 3. Railcars are provided with both a coupler and a brake pipe, and both are connected to the coupler and brake pipe of an adjacent railcar to achieve the desired utility. The couplers are commonly situated within a rigid housing that allows for limited side-to-side motion, on the order of 10 degrees rotation off of the direction of travel, to enable both connection to the adjacent railcar and necessary connection flexibility during transport. An example of a prior art coupler within a housing is shown in FIG. 1b, the coupler 8 situated within a housing 5 and retained between housing walls 6 and 7 to limit side-to-side rotation of the coupler 8 while allowing projection of the coupler head 9.
While it is common to see such couplers projecting forwardly and/or rearwardly of railway cars, it has been found that there are situations where such projection is undesirable. For example, in the case of so-called road/rail vehicles which can be driven on either rails or flat road surfaces due to the presence of both rail wheels and rubber tires, the projection of an unused coupler may result in a total vehicle length that exceeds highway use regulations. Also, certain maintenance of way equipment might benefit from a selectively projectable coupler.
What is needed, therefore, is a means for selectively projecting a coupler in a rail-supported vehicle.